principle-tdd

What problem does it solve?

It solves the risk of building software without fast feedback by enforcing a Test-Driven Development loop that makes behavior precise, regressions obvious, and design seams explicit.

Core Features & Use Cases

• Red-Green-Refactor loop: Write a failing test first, implement the smallest passing code, then refactor only when all tests are green.
• F.I.R.S.T. test quality: Ensure tests are fast, isolated, repeatable, self-validating, and timely.
• Pragmatic test doubles: Choose fakes, stubs, spies, or mocks based on the cheapest double that proves the behavior.
• Design feedback from mocking: Treat difficult mocks as signals of bad seams, leaky abstractions, or missing interfaces.
• Outside-in vs inside-out TDD: Select the direction that has fewer unknowns for your specific task.

Quick Start

Ask your AI to walk through the next TDD cycle by writing the Red test, then the minimal Green implementation, then the Refactor steps while keeping all tests green.